Amelia Anne is Dead and Gone by Kat Rosenfeld (Dutton Children's hardcover, 5 July 2012).
I was immediately attracted to this book by the title, which sounds like it might be the title of an old folk song (but isn't, according to my research).
Her plan is tainted first by her boyfriend James breaking up with her on graduation night. Later that night (or early morning) an battered and unidentifiable young woman's body is discovered just outside of town, not far from the place where Becca and James had been parked.
Doubly shadowed, Becca's summer turns into a haze of making up-breaking up with James and dealing with the after-effects of the murder on herself, her family and her friends. For although the the murdered woman was not a local, all evidence indicates that the killer knew the area well. Thus the town is rife with suspicion, particularly towards the residents of the nearby lake resort.
Having grown up in small towns, I'm well acquainted with the insularity that Rosenfeld describes, as well as the aching need to get away if one hasn't lived anywhere else.
But the most wonderful thing about this book is Rosenfeld's evocative, lyrical prose, which proves that some of the best literature being published today is aimed at young adults.
FTC Full Disclosure: I borrowed this book from my local library.